These nicely made nickel plated steel screws are the most common size you'll find out there. They fit every Kluson style tuner I know of exactly. I measured exactly 2.5mm on the main threaded portion of the shank. Length of threads is around 10mm. Head diameter around 4.38mm. These screws are also great for installing P90 'dog ear' pickups! A set or two is a must for your roadie kit of parts.